by Chip Walter
V
Tears
Chapter 9
The Creature That Weeps
Why the heck do people cry? It is such a weird thing to do. You get upset and water comes out of your eyes.
—James Gross, clinical psychologist, Stanford University
The advantage of the emotions is that they lead us astray.
—Oscar Wilde
Scientists are compelled to admit they really don’t understand why we cry. They can only agree that we are the only animal that does. Other animals may whimper, moan, and howl, but none cries tears of emotion, not even our closest primate relatives. And unlike laughing or even speech, there doesn’t seem to be any obvious analog in the primate world. Apes do have tear ducts, and so do other mammals, but they are there purely for housecleaning: Tears bathe and heal the eyes. We have similar plumbing in place to keep our eyes clean and disease-free, but for some reason, at some point in our evolution, a savanna ape, or perhaps an early version of our own species, developed a direct, physical connection between the gland that makes our tears and the emotional parts of our brains. That is unique in nature.
Like every genetic mutation, this connection was a mistake. But a mistake that worked, an adaptation that somehow enhanced the survival of the creature that ended up with the wayward gene, which it then passed along to other generations until it became not an aberration, but a successful trait.
When emotions overwhelm us, a small organ called the lacrimal gland, which sits just beyond the outer corner of each eye, can generate so many tears that they fill, and overflow the ducts that rim the southern hemisphere of our eyes. This is what makes human crying so unusual. Many animals can feel longing, fear, or pain. But it is the tears, combined with our emotions, that makes human crying unlike any other natural behavior.
The very first thing a baby does when he enters this world is cry. It is a primal, unmistakable announcement that he has arrived.1 The birth cry signals two simple things: the child is alive, and the umbilical cord can be safely cut, which marks us as a whole and separate human being. During the first three to four months of life, before we learn to smile or laugh, crying is the primary communication method we have. But between eight and twelve months we begin to cry less as we develop other ways to express what we want—by pointing or grunting, or tossing spoons, cereal, and bottles around. But in our earliest days, we use crying often and with great effect.
An infant’s cries work so well partly because parents’ ears are attuned to the bawling of their children. Nature has rigged it this way. Human mothers can almost always distinguish the cries of their own infants from the cries of others. Babies even have different cries that send different messages—shrieks and screams of pain that mean something is seriously wrong, or cries of separation, discomfort, and hunger. Each cry becomes a kind of rudimentary, wailing vocabulary that precedes a baby’s first words. In fact, some linguists have theorized that the rhythmic rising and falling pitch of an infant’s cries form the basic intonation pattern for all human sentences, which normally begin on an ascending note and then end on a descending one. When these cries are combined with the pained, reddening, puckered faces that often go with them, the two can garner a lot of very focused attention. (This face, it turns out, resembles the “frustration-sadness,” “whimper,” and “cry” faces of apes.2)
As we grow older our reasons for crying become invested with more subtle shades of feeling. Our pain and discomfort is no longer simply physical, but also emotional. And it is almost always inexplicable. We cry, it seems, because our emotions have outflanked the simple syntax of speech. Nouns and verbs and adjectives, and the logic that goes with them, simply aren’t up to the job of explaining our feelings. If we could use words, we might not need to cry at all. But, of course, we do because crying, like laughter, is a primal form of communication that taps the emotional, mute, and unconscious parts of our brains and experience.
In fact, electromyographic studies show that the nerves that operate the muscle that makes our chin quiver when we are on the verge of tears (the mentalis muscle), or that put the lump in our throats or depress the corners of our lips (depressor anguli oris muscle), are all very difficult to consciously and purposefully control. Yet the slightest disappointment instantly reveals itself in the expression of downturned lips. In fact our mentalis muscle never really stops moving, which is another way of saying it is an entirely unconscious physical representation of our emotions. These nerves and muscles simply don’t check in with the verbal and conscious parts of our mind before doing what they do. This is why even when babies are born without structures above the midbrain they can still cry, an indication that the feelings associated with crying run deep into our evolutionary history, long before the apparatus of speech and conscious thought emerged.3
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Tears also serve a physiological purpose as part of the support system that operates our eyes. The rods and cones, the optic nerve, and the intricate geometries that enable us to perceive light are all amazing evolutionary innovations, but they couldn’t function if it weren’t for tears.
To look at them (and through them) the lenses of the human eye appear perfectly smooth, but in fact they are pocked and rutted and wrinkled, moonlike in their geography. But our tears fill in and smooth out the imperfections of our lenses every time we blink, an average of twelve times per minute. Without their steady drip, the world would look as if we were peering through a plastic bag, and we would have, roughly, the visual acuity of Mr. Magoo.
Tears do not consist entirely of water; they are actually a kind of “fluid sandwich” made of three separate layers. The inner layer, the part of the sandwich that bathes the cornea, or lens of the eye, consists of a lubricant called mucin. The middle layer is mostly water, and the outer layer, over which the lids of our eyes fold, is made of oils evolved to keep our tears from evaporating. If our tears were not incessantly lubricating and cleansing our eyes, we would quickly and painfully lose them to infection and disease.
Just as our tears have three layers, tears themselves come in three varieties: reflex, basal, and psychic. Each is unique in its purpose and its chemistry. Reflex tears that form when we get shampoo or a grain of blown sand in our eye, are produced automatically in the main lacrimal gland to flush the eye and help heal any damage. Basal tears stream continuously over our eyes so we can see clearly, and they dampen and remove dust and debris. Psychic tears are the ones that confound scientists. They well up when we experience strong emotion—mostly sadness, it seems—but also when we feel intense pride, anger, frustration, or love and warmth.
Whatever the reasons for our tears, they all flow from the same intricate lachrymal system—canals, glands, and nerves with otherworldly names like the glands of Zeis, or the crypts of Henle. The lachrymal gland itself produces most of the tears we shed when our eyes are irritated or we feel our deepest emotions. Basal tears drip continuously from a system of tiny glands at the top of the eye and combine with fluid from goblet cells, the glands of Manz, and forty-six additional glands to create a complex plumbing system that keeps our vision clear and our eyes free of disease.
Most tears eventually find their way to the canals at the bottom of our eyes near the bridge of our nose, where they then drain through the puncta, the lip of tissue at the edge of our eyes. From there they journey through the lacrimal sac, past the valve of Hasner, and into our nose, which explains why crying hard leads to runny noses.
The whole system, however, can handle only so much water. It empties tears at the paltry rate of a microliter and a half per minute, a droplet only slightly larger than the tip of a ballpoint pen. If we cry heavily, the system overflows and our tears well up and spill down our cheeks. As it turns out, this is extremely important because visible tears are crucial to human communication.
Scientists categorize the kinds of tears we cry not only according to their purpose or the events that cause them, but also by their chemical makeup. Reflex tears, like ba
sal tears, come loaded with globins and glucose, antibacterial and immunological proteins, urea, and lots of salt. But emotional tears have a different chemical makeup. In fact, the tears we cry when we are upset, as opposed to when we get a sharp stick in the eye, have 20 to 25 percent more proteins. They also have four times the amount of potassium normally found in blood plasma, and thirty times the concentration of manganese. Psychic tears brim with hormones—adrenocorticotropic hormone (ACTH), for example, an extremely accurate indicator of stress, and prolactin, which controls the neurotransmitter receptors in the lacrimal glands that release tears in the first place. The strange thing is that prolactin is also the hormone that makes it possible for women to produce breast milk.
Scientists believe that these cocktails of hormones and proteins are linked to the moods, stresses, and emotions we often associate with crying. High concentrations of manganese, for example, show up in the brains of people suffering from chronic depression. Too much ACTH is an excellent indicator of increased anxiety and stress. And studies show that women—all of whom have higher levels of prolactin than men—cry about five times as often. In fact, women unfortunate enough to have inordinately high levels of prolactin also experience more intense hostility, anxiety, and depression, which can lead to still more crying.
There’s another perplexing connection between prolactin and tears: when the child of a breast-feeding mother cries, the mother’s milk reflexively “lets down,” so that it becomes immediately available to the baby. In other words, the mother’s body instantly and reflexively prepares itself to relieve the infant’s reason for crying, or at least the most likely one. Some mothers even claim to experience a kind of telepathy with their infants, times when their milk lets down even when they are traveling or at the office running a meeting miles away from their infants. They report that on checking in later, their milk let down at precisely the time their baby started to cry.4
Just as different reasons for crying result in chemically different tears, different parts of the brain—the seat of our experience—are physically connected to the feelings that make us cry. Nerves linked to our lacrimal glands rope their way by long, roundabout routes into both ancient and newly evolved areas of the brain—the pons, basal ganglia, thalamus, hypothalamus, and prefrontal cortex. Each of these areas are themselves important cerebral routing stations that handle functions and experiences as diverse as facial expression, breathing, body temperature, sight, swallowing, and reflection, memory, planning, and worrying. So it is no accident that so many kinds of feelings can cause us to cry. Nor is it an accident that those feelings affect our body temperature and blood pressure, heart rate and facial expressions, at the very same time as they evoke more memories and emotions—many of them confusing and contradictory.
When we cry, some of the hormonal cocktails that are driving the feelings we experience actually find their way into our tears. Biochemist William Frey, who directs the Dry Eye and Tear Research Center in Minneapolis, believes that one of the reasons why we feel better after we weep is because we are literally crying out the extra hormones and proteins in our brains that generate the feelings that saddened us in the first place. This explains why, he says, we sometimes advise one another to “Go ahead. Have a good cry.” Emotional tears are the body’s way of flushing out the chemicals that make us sad—the excess prolactin, manganese, and ACTH.
Crying Factoids
Though crying is poorly researched, a few studies have yielded some interesting statistics. For example, do women cry more often than men? Dr. Frey and his colleagues worked with 331 volunteers, aged eighteen to seventy-five, and asked them to keep a “tear diary” for thirty days. Women reported crying four or five times more than men that month. Frey theorizes the reasons are more chemical than cultural. Women have much higher levels of serum prolactin than men, and prolactin is a hormone connected with the production of tears as well as breast milk. “Hormones may help regulate tear production and have something to do with crying frequency.” The fact that there is very little difference in the rates of crying among boys and girls bolsters Frey’s argument. Until about age twelve prolactin levels are about the same no matter the sex, but between the ages twelve and eighteen women develop levels 60 percent higher than men and cry more often.
Based on Dr. Frey’s “tear diaries,” participants reported that they cried because they were sad 49 percent of the time; out of happiness 21 percent of the time; in anger or sympathy, 10 and 7 percent, respectively; and because of anxiety or fear, 5 and 4 percent, respectively. The remaining reasons for crying were unaccounted for.
According to another study, a happy cry averages two minutes; a sad cry, seven.
Not everyone agrees with the theory that emotional tears drain out the hormones and proteins that made us sad. If, for example, you find yourself crying over the death of a close friend as you recall the good times you shared, scientists wonder if it is your memories generating the hormones that make you sad, or the other way around? There is no absolute way to know. It may be both since, in effect, the brain is a tremendously complex feedback loop (hundreds of millions of loops within loops, really) that continually interact with the world outside and its own kaleidoscopic experiences inside. Perhaps feelings generate hormones, and hormones generate more intense feelings until we finally burst into tears.
Randolph Cornelius, a psychologist at Vassar College, has been investigating the profound emotions that emerge out of crying’s intricate neuronal alchemy since he began researching his doctoral dissertation some twenty-five years ago. During the earliest days of his work he made one simple request of the subjects he was studying: Tell me about the last time you cried in front of another person. The heartbreaking and harrowing accounts of life at its extremes often brought him to tears himself at the end of the day.
There was a young woman, for example, who told him of the day when she was barely nineteen, standing in a hospital with her six-month-old infant in her arms, and gave doctors permission to remove life support for her husband, who was dying of cancer and had suffered a heart attack. She held her tears, she told Cornelius, until she had signed the papers, and then fell apart in the arms of a nurse whose name she never knew.
During another interview a Vietnam veteran told how he had had half of his face shot away during a firefight in Vietnam. He lost an eye and had a metal plate implanted to replace the portions of his skull that had been shattered. One day, he told Cornelius, he made a call to his therapist. He planned to leave a message telling her that he was committing suicide. She unexpectedly answered the phone, and in the conversation that followed, he had a major breakthrough. When he did, he told Cornelius, he could feel “hot tears rolling down my cheeks.” But the thing was, he said, he knew he was missing the eye from which he felt tears were falling.
A powerful sense of empathy and sympathy is a uniquely human reaction to the tears of others. Crying often begets more crying, possibly because the mirror neurons that long ago made it possible for our ancestors to learn how to make a tool also enable us today to put ourselves into one another’s emotional shoes.
This makes human crying an unusually potent form of communication. More than anything, tears reveal us at our most vulnerable. Laughter bonds us, and it can bring us progressively closer, but crying binds us in another, deeper way: It is an unmistakable plea for help, an expression of utter vulnerability. Tears in some intense and commanding way communicate an opportunity for intimacy and authenticity that is more powerful than any words could be. When we cry, the walls are down, and the defenses have been breached.
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Whatever the reasons why we cry, it is difficult to argue that tears alone can sufficiently flush the hormones from our bodies to provide the sense of relief we feel after crying. Our tear ducts simply aren’t that big or that efficient. Even a good, long, heaving bout of crying doesn’t add up to more than a thimbleful of hormone-laden fluid.
Yet it is almost always true that we do feel bett
er after we cry, even if only temporarily. When dealing with terribly sad situations, a death or the loss of a relationship for example, crying at least seems to bring us a breather, a chance to regroup emotionally. But if we don’t feel better because we have flushed our systems of the chemistry that causes our sadness, what’s the source of the relief?
One explanation is that we may not only cry hormones out, we also may cry them in. Frey also has discovered that the neurotransmitters leucineenkephalin (a natural opiatelike substance that relieves pain) is released in the brain when we weep. These neurotransmitters are like the ones that laughing generates, though obviously for different reasons. But the effect is similar: They improve our mood. At first blush it is a mystery why this should make good evolutionary policy. After all, what purpose would mood swings serve for an animal when it comes to surviving predators and disease? Not much, unless that animal happens to be as intensely social and intelligent as we are.
In nature, it is generally good to maintain a state of homeostasis—to remain neither too hot nor too cold, too active nor too lethargic. And if there have to be swings in one direction or another, it is best to at least keep them under control and get back to normal as quickly as possible. If open living systems including bacteria, trees, ocean reefs, and humans fail to rectify extremes that pull them too far from their normal style of living, they will, and do, unravel and die. A plant may freeze, a lizard may overheat, a forest may be denuded, and a human might become so emotionally undone he can’t function effectively.
In a species whose survival depends on maintaining stable relationships, equilibrium embraces more than just physical comfort, it also embraces psychic comfort. Our need to maintain homeostasis explains why we eat and sleep, why we invented shelter and clothing and air conditioning, and it may help explain why we cry.